The Sample Analogue Curation Facility (SACF) leads the curation of ESA’s Exploration Sample Analogue Collection (ESA2C) of planetary regolith analogue and simulant materials. The ESA2C collection is comprised of a series of geological samples designed to represent planetary surface materials (regolith) by replicating some of their properties.
These properties can be classified into 1 of 3 groups: Mechanical, Spectral, and Chemical. Mechanical properties are related to the material’s physical aspects such as density, porosity, grain shape and size distribution, and shear strength. Chemical properties relate to the minerals and phases present in the material, and often includes modal mineralogy, individual mineral chemistry, bulk sample chemistry, and volatile contents. Spectral properties represent how the samples interact with electromagnetic radiation of a variety of wavelengths, and is often the most sensitive to changes of other properties. For example, a slight change in mineral chemistry or porosity can result in highly varied spectral properties, but may not alter the mechanical properties of a material. Research at the SACF is currently underway to further understand the properties of planetary regolith, and investigate how these findings can be applied to generating more representative regolith simulants for the ESA2C collection.
There are currently 18 types of geologic materials (or parent samples) within the ESA2C collection, with over 200 individual samples covering a range of planetary surface types and materials. Most of these samples are available to loan for research and technology development projects in the field of planetary science and exploration: please visit the ESA2C Loan Information page for more details. Many samples are also available for public outreach activities, and some are suitable for instrument calibration purposes.
To date, many of the samples in the collection have been designed as mechanical or ‘general-purpose’ simulants. These materials are present in the greatest mass as they are often required in large quantities to test mechanical components; planetary rovers and deep drills are 2 such examples. The SACF has plans to develop more of the chemically- and spectrally-similar simulants for the ESA2C collection in the near future.